The effects of prescribed burning on rare plant populations

Joshua P. Scholl, Plant Science and Conservation, Chicago Botanic Garden, Glencoe, IL, Logan Novak, Plant Biology and Conservation, Northwestern University, Evanston, IL, Gretel Kiefer, Chicago Botanic Garden and Amy Iler, Northwestern University, Evanston, IL

Background/Question/Methods
Rare species serve important ecosystem services, including community resilience to global change. Rare species are disappearing globally because of anthropogenic activities such as fire suppression. Prescribed burning is a widespread management approach that can reduce invasive plant presence, recycle nutrients into the soil, and bring back species diversity. However, the effects of prescribed burning on rare plants are not well understood. We analyzed the population dynamics of 84 rare, native plant taxa in response to prescribed burning using the Chicago Botanic Garden’s Plants of Concern dataset. This dataset encompasses rare plant taxa in the states of Illinois, Indiana and Wisconsin, USA. We evaluated the effects of burning on changes in population sizes by comparing population sizes one, two, three, and four years after prescribed burning to unburned populations for each taxa. We also evaluated the effect of habitat (forest, dune, prairie, savanna, wetland) on population size. We complemented this analysis with a literature review of fire responses for available taxa.
Results/Conclusions
Our analyses showed that the population size of 20 taxa was significantly affected by prescribed burning. Many of these taxa responded positively to fire (12) and responded significantly one year after burning (13). Across all models, habitat was a significant additive effect for only four species. Our literature review revealed 10 taxa with published responses that overlapped with the 20 taxa showing a significant response in our analyses. Of these ten taxa, seven agreed with our burn response findings. The contrasting results found for the other three taxa stem from longer term fire responses (10+ years after burning) evaluated in different regions of the country. Overall, the majority of species that were significantly affected by burning had increased population size and responded one-year after burns. Therefore, burning has potential to increase rare plant population size in the short-term, but managers should evaluate which rare species are present before considering burns.